Modular power distribution system for use in computer equipment racks

ABSTRACT

A modular power distribution system is provided for distributing power within an equipment rack. A control unit is mounted within the rack having a power input connected to a power source and a converter for converting the input power to a power supply for the rack equipment. The control unit includes a housing and power outlets are provided for electrical connection to the control unit and distributing the converted power supply to the equipment. One or more extension bars are mounted within the rack adjacent a corner support of the rack. The extension bar includes a power inlet and is connected via an electrical conductor to one of the power outlets of the control unit. The extension bar includes a number of power outlets (such as up to or more than 8) adapted for electrical connection to power supply lines (cords or hardwiring) from the rack equipment.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates, in general, to power distribution anddistribution systems, and more particularly, to a modular powerdistribution unit for use in distributing power within the limited spaceof an equipment cabinet or rack, such as a computer equipment rack or adata storage cabinet.

2. Relevant Background

In the computer industry, mass storage systems and other computersystems typically include numerous multi-shelf cabinets or racks eachholding multiple devices or enclosures, such as servers, disk drives,and other computer devices. These racks or rack systems are ideal formodular projects and are designed to accept standard sized deviceshaving relatively standard power requirements and communicationconnections. Generally, the outer case includes an aluminum or steelframework fitted with covers and a series of connectors at the rear fromwhich the devices or modules derive their power and exchangecommunication signals. The individual modules include a supportingchassis or housing that slides into the rack and is supported on guides,such as clip-in glides. Racks and rack systems are inherently flexiblebut are often expensive which drives users and rack manufacturers toefficiently use space within the rack or cabinet.

Each rack or cabinet typically only has a limited amount of space thatis defined by or arranged into shelves. The shelves or shelf locationsare configured to allow a device enclosure or module or other componentsto be plugged into and supported within the rack. Typical rackconfigurations call for 14 shelves although more shelves may be providedsuch as up to 24 or more shelves. If shelves are arranged vertically, atypical cabinet may have 14, 24, 32, or some other number of shelvesthat each occupy a certain amount of rack space, such as 3 retma (U)which is a standard mounting unit increment.

In practice, such as data centers, data storage, and the like, the racksare often densely packed with devices, such as servers, each requiring aprimary power supply and a backup power supply for redundancy. Forexample, one arrangement uses up to 14-3U server enclosures in a rackrequiring up to 28-750 watt power supplies. In another rackconfiguration, 21-2U servers are installed in a rack with 42-500 wattprimary and redundant power supplies. A major challenge facing rack andequipment designers is how best to serve dense equipment users so as toprovide increased power distribution while efficiently using the spacewithin the rack to reduce cable clutter and connection and supplyconfusion. In other words, it is desirable to reduce the amount of spacerequired for power distribution units (PDUs) (e.g., typically, aplurality of electrical receptacles to which electrical plugs of powercords can be connected and which are supplied by an inlet A/C powersource) and power cords from the PDUs to the devices on the rack shelvesto thereby free up rack U-space for more modules or enclosures.

Existing forms of power distribution require large volumes of cabinet orrack space as numerous PDUs are provided and often mounted in the rackthat reduces the available shelves or U-space for computer or otherdesired components. For example, current PDU support requirements oftencall for as many as four to six 24 amp PDUs per rack, which leads tosome rack configurations being limited when a maximum number of PDUshave been installed in the rack. In addition to the space required forthe PDUs, large volumes of rack space may be required for the largenumber of power cords and other devices required to connect the PDUs tothe individual devices or loads on the shelves. Often, an enclosure ordevice is located on a shelf which is relatively distant from theclosest PDU which requires a long power cord to be snaked through therack to the enclosure or device. The number of the cables and PDUsincreases deployment complexity and can cause connection problems andmistakes. Additionally, after installation is completed, laterexpansions or modifications to the rack and power distributionarrangements are difficult to successfully implement.

Hence, there remains a need for an improved method and system fordistributing power within an equipment rack or cabinet that requiresless U-space, reduces the number and lengths and cost of connectingpower supply cords used in racks (i.e., provides improved cable or cordmanagement), is simple to customize, to install, and upgrade or latermodify, and reduces the total deployment cost.

SUMMARY OF THE INVENTION

The present invention addresses the above discussed and additionalproblems by providing a modular power distribution system for use indistributing power to devices, modules, and/or enclosures mounted withinequipment racks or cabinets. The power distribution system includes twobasic building blocks: a core or control unit and one or more (and,typically 2 or 4) extension sticks or bars. The modular architectureallows a rack designer to custom configure a rack power distributionsystem based on their particular computer or other equipment needs andpower availability, which minimizes cable clutter and confusion andincreases available rack space.

Generally, the modular power distribution system concentrates centralfeatures of typical power distribution systems (e.g., a main powerswitch, circuit breakers, load groups, and power-on indication) into thecore unit that is configured to be mounted at a remote location withinthe rack or cabinet enclosure. The housing of the core unit is thin,such as 1U or less, and includes clips or brackets for mountingvertically on a side of the rack (e.g., a 0U mounting) or horizontally(e.g., a 1U or less mounting). The extension bars include a number(e.g., 1 to 8 connections are provided in some embodiments) of AC poweroutlets, receptacles, connectors, cord segments, or other devices forconnecting enclosures, modules, or devices in the rack to a powersource. The extension bars include clips or other fasteners for mountingonto one corner support of the rack, which avoids using rack U-space forthe extension bars while also enabling positioning of the bars at nearlyany height within the rack and typically, near the rack positions orshelves of the devices being powered to reduce the need for long lengthsof power supply cords and extend outlets along the entire or any desiredportion of the length of the rack.

In operation, the core unit provides protected outputs that feed powerto multiple high current outlets in the extension bars that can be usedfor connecting the high current loads, e.g., the enclosures, modules, ordevices mounted on the shelves of the rack, to an acceptable powersupply or source. The extension bars each connect directly to the coreunit via a flexible power supply cord. The extension bars effectivelylocate the “fanning out” of the AC power in the rack closer to the loadsand eliminates many power supply cords that were required in previousdistribution arrangements. A wide range of capacities may be providedaccording to the invention (such as 16 to 40 amps devices) and numerousoutlets may be provided in each modular power distribution system, suchas 32 outlets with the used of 4 extension bars each having 8 AC poweroutlets (which in turn may be any of several industry standard connectorfamilies or be short power leads that connect directly to the load whenit is desired to eliminate power cords).

More particularly, a power distribution system is provided fordistributing power to electrical or computer equipment in an equipmentrack. The system includes a control unit mounted within the rack havinga power input electrically connected to a power source (such as with acable or hardwired to an AC power source or facility source) and aconverter for converting the input power from the source to a powersupply required by the rack equipment. The control unit includes ahousing on which a plurality of power outlets or connections are mountedfor providing an electrical connection to the control unit and fordistributing the converted power supply to the equipment. An extensionbar is mounted within the rack typically adjacent one of the cornersupports of the rack. The extension bar includes a power inlet and isconnected via an electrical conductor or power cord to one of the poweroutlets of the control unit. The extension bar includes a number ofpower outlets (such as up to or more than 8) adapted for electricalconnection to power supply lines (cords or hardwiring) from the rackequipment. The control unit housing typically includes one or morebrackets for rigidly mounting the housing to the corner supports of therack. In some embodiments, the control unit is mounted vertically in a0U mounting with the thin (i.e., less than about 1U) cross-section ofthe housing positioned between two adjacent corner supports. In otherembodiments, the control unit is mounted horizontally in a less than 1Umounting with the thin cross-section of the house position horizontallybetween the corner supports.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a functional block diagram of a modular power distributionsystem according to the present invention;

FIG. 2 is a partial perspective view of one embodiment of a modularpower distribution system, similar to FIG. 1, installed in a typicalequipment rack or cabinet showing the side mounting arrangement of thecore or control unit;

FIG. 3 is a perspective view similar to that of FIG. 2 illustratinganother embodiment of a modular power distribution system showing the“1U” or horizontal mounting arrangement of the core or control unit;

FIG. 4 is a front perspective view of a core unit, as would be used inthe systems of FIGS. 1-3;

FIG. 5 is a rear perspective view of the core unit of FIG. 4;

FIG. 6 is functional block diagram of equipment in a rack illustratingthe use of a pair of control units of the invention to provide primaryand secondary or backup power to four enclosures, such as servers; and

FIG. 7 is a functional block diagram similar to FIG. 6 illustrating theuse of a pair of modular power distribution unit of the invention todistribute power to three enclosures, similar to FIG. 6, but alsoproviding a number of other rack options or devices.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is directed toward modular power distributionsystems for use in equipment racks, such as those typically utilized inthe computer and data storage industries, and rack designs incorporatingsuch modular systems. The modular systems are unique in utilizing twobuilding blocks to allow ready field configuration and placement ofpower outlets within a rack. The first building block is control unitthat provides the connecting point to a power supply outside the rackand includes a number of control and distribution components such asmain power switch, circuit breakers, load groups, and remote powermonitoring and management (such as via a network like the Internet orother communication network). The control unit has a thin housing withmounting brackets that allow the unit to be mounted either in a verticalor side mounting in the rack (“a 0U mounting”) that does not use anyrack space or a horizontal or in-rack mounting (“a 1U mounting”) thatuses a small portion of the rack space. The second building block is aset (e.g., 1 to 4 or more) of extension bars or sticks that areconnected to the control unit and include a number (such as 1 to 8 ormore) of power outlets, receptacles, and the like to distribute power tonumerous locations in the rack. Similar to the control unit, theextension bars include housings with clips or brackets that allow theextension bars to be mounted on vertical structural members (e.g.,corner supports) of the rack at varied heights to place the outlets nearthe rack loads, e.g., enclosures, modules, and other rack-mounteddevices and equipment. The modular system addresses the problem of cablemanagement by significantly reducing the number of cords and cablesrequired and reducing the lengths of cables in the rack, which improvescooling in the rack and frees up additional rack U-space.

More specifically, FIG. 1 illustrates a modular power distributionsystem 100 in functional block form as the system 100 may be integratedinto an equipment rack 110. The equipment rack 110 may be any of anumber of widely available equipment racks used in the computer andelectronics industry, such as the Compaq Rack 9000 and 10000 Series. Therack 110 generally includes space or shelves on or in which equipmentmodules or enclosures are positioned, with an industry standard being 3retmas equaling 1U. An important design configuration for many racks isattempting to utilize all or most of the rack U-space or shelves withfunctional equipment (such as computer servers, controllers, and thelike) and not with support or peripheral equipment, such as powerdistribution devices and power supply cables.

With this space requirement in mind, the power distribution system 100includes a control or core unit 120 which centralizes numerous powerdistribution, power distribution and load monitoring, and controlfunctions within a single device and includes one or more power supplysticks or extension devices that provide power from the control unit 120to a number of loads or enclosures (not shown in FIG. 1) mountedthroughout the rack 110. As will be discussed with reference to FIGS.2-5, the control unit 120 typically includes a relatively small housing(such as 1U or less thickness) and mounting brackets compatible withstandard racks 110. The combination of small size and mounting bracketsallows the control unit 120 to be mounted in numerous locations withinthe rack 110 in a vertical or side arrangement (“0U mounting) betweentwo corner supports of the rack 110 that takes up no or little rackU-space or in a horizontal or shelf arrangement (“1U mounting”) thattakes only 1U or less of rack U-space.

The control unit 120 provides a power supply function within the rack110. The unit 20 is connected to power source 140 by power cord or cable144. The control unit 120 functions to brings power into the rack 110from power source 140 (e.g., any of numerous power sources used in thecomputer equipment and data storage industries) and then converts thepower received from power source 140 to a power supply useful ordemanded by loads in the rack 110. To this end, the control unit 120includes converter 122 to convert the input power (such as 30 to 50 ampAC) on cable 144 for distribution on power supply cables 152, 156, 162,172 to extension bars 150, 154, 160, 170.

The control unit 120 provides protected outputs that feed power via theconverter 122 to multiple current outlets (typically, high currentoutlets) on the control unit 120 that can be used to connect toindividual high current loads (not shown in FIG. 1 but see FIG. 6) or tothe extension bars 150, 154, 160, 170 via flexible cords 152, 156, 162,172, respectively. Each extension bar 150, 154, 160, 170 includesmultiple power outlets (e.g., AC power outlets) to locate the “fanningout” of the AC power closer to the load and eliminate multiple long runsof individual power cords. The power outlets may be any of numerousindustry standard connector families or be short power leads that canconnect directly to the load to eliminate the need for power cords. Aswill discussed with reference to FIG. 2, the extension bars 150, 154,160, 170 are configured for mounting on corner supports of the rack 110with clips or other brackets and may be mounted at user-selected heightsto allow ready customization of the power distribution system 100 and toplace the extension bars, and therefore, power outlets, near to loadswithin the rack 110.

The number of extension bars 150, 154, 160, 170 may be four, as shown,or any other useful number (such as 1, 2, 3, 4, 5, or more) as long asthe total current does not exceed the maximum allowable current draw orcurrent rating of the control unit 120. Similarly, the number of poweroutlets can vary, and in one embodiment, 8 outlets are provided on eachextension bar 150, 154, 160, 170, which provides 32 outlets (or supportfor 32 loads) with one control unit 120. A receptacle fan-out device 178may be connected to an extension bar, such as bar 170, to enableadditional loads to be supported by the power distribution assembly 110.The device 178 may be any industry accepted power supply device, such astypically plug-in outlet centers, power outlet strips, UPS products, andthe like.

To fulfill this power supply or distribution function, numerousconfigurations can be used for the control unit 120 and converter 122and for the extension bars 150, 154, 160, 170 (as well as the number ofsuch bars or sticks). The embodiments may range from lower input powerdensity (such as a 16 amp input with 1 or 2 expansion bars) up to highinput power density (such as 3-phase input supporting up to 6 extensionbars). With this broad range of inputs and outputs, the following arejust a few exemplary (but not limiting) examples of how the powerdistribution function may be provided in a system 100. One embodiment isdesigned to connect low voltage (i.e., 100 to 127 AC voltage) powersources and/or directly into a facility outlet (i.e., power source 140)via cord 144 and a single input on unit 120 (such as a NEMA L5-30P orthe like) and four outputs (such as four IEC320-C19 outlets at 12 ampseach). This embodiment typically has a relatively low maximum current orcurrent rating (such as 24 amps) with the output being up to 32 outletssuch as 8 NEMA 5-15 or other outlets on the bars 150, 154, 160, 170 withmaximum outlet and bar currents (such as 12 amp maximum per outlet and12 amp maximum per bar).

In another embodiment of system 100, a higher input voltage (such as 200to 240 AC voltage) is input via cord 144 from power source 140, which istypically the facility input, and having four outputs (such as fourIEC320-C19 outlets at 12 amps each). In this embodiment, the maximumthrough current may again be set at 24 amps with each extension bar 150,154, 160, 170 having up to 8 IEC 320 C-13 or other outlets with maximumoutlet and total extension bar currents (such as 10 amps per outlet and12 amps per bar). In another embodiment, the maximum current through thecontrol unit 110 is set at 32 amps with single input (such as an IEC309-32A) provided in the control unit 110 with four outlets forconnecting to power supply cords 152, 156, 162, 170 and each extensionbar 150, 154, 160, 170 having 8 outputs or outlets (such as 8 IEC 320C-13 or similar outlets). In another example, the control unit 110 isdesigned to hardwired via cord 144 to the power source 140 (such as thefacility input or a high voltage UPS). The input connection on the unit110 then may be a field wired terminal and the maximum current for theunit 110 may be higher, such as 40 amps and the input voltage higher,such as 200 to 240 volts AC. In this example, the extension bars 150,154, 160, and 170 may not be identical with three having 8 outlets (suchas 8 IEC 320 C-13 outlets with a maximum outlet current such as 10 amps)with a particular maximum bar current (such as 12 amps) and with thefourth bar having fewer outlets (such as 4) with but with higher currentratings (such as 4 IEC 320 C-19 outlets having a 12 amp rating). In thismanner, loads having differing power input requirements can be mountedwithin a single rack 110 and supplied power effectively with a controlunit 120 with differently configured extension bars 150, 154, 160, 170.These are just a few examples of the configurations for the powerdistribution system 100 and are not intended to be limiting but todemonstrate the flexibility of the system 100 to distribute power atvarying locations and to differing types of loads within the rack 110.

As shown, the control unit 120 includes an overload protector 124 andoutput circuit breakers 126 to more effectively provide the powerdistribution function in the system 100. More particularly, the overloadprotector 124 and output circuit breakers 126 provide input overcurrentprotection, surge protection, and load segment output overcurrentprotection. The overload protector 124 may be any device or circuitthat, for example, disconnects the control unit 120 from the powersource 140 when the current or voltage becomes excessive (over designlimits for the control unit 120). The output circuit breakers 126 areprovided to open the circuit to the outlet receptacles or connections tothe extension bars 150, 154, 160, 170 via cords 152, 156, 162, 172, andthe number and rating of the output circuit breakers 126 may vary tosuit the allowable current in the bars 150, 154, 160, 170 (e.g., in 12amp embodiments of the bars, 15 amp or smaller circuit breakers may beprovided for each outlet receptacle in the control unit 120). Althoughnot shown, the control unit 120 may include line fail-over switchingdevices or circuits along with multiple utility feeds for redundantpower supply or source configurations (e.g., by adding an additionalpower source 140 and source line 144).

In addition to rack power distribution functions, the control unit 120in some embodiments is configured to facilitate a number of remotemonitoring and/or remote management or operation functions. Generally,such remote management and monitoring functions may include load segmentcontrol (e.g., on/off control), automatic or manual staggered startup ofeach output from the control unit 120, line status monitoring, linevoltage measurements, power consumption monitoring, and other desiredmanagement and monitoring functions. An operator or monitor can view theresults of such monitoring and remotely operate the control unit 120from remote monitoring and control node 190 (such as a typical computerdevice with I/O devices such as keyboards, graphical user interfaces,and the like, with a processor and memory, and a monitor). Operator node190 is linked to the control unit 120 via the communication network 180,e.g., any digital data communications network, wired or unwired, such asthe Internet, a local area network (LAN), a wide area network (WAN), andthe like, and communication links 182 and 186. Alternatively, localmanagement via the user node 190 may be provided with a directconnection (such as at a serial interface 132 at the control unit 120 tomonitoring and/or management cards in the unit 120).

A communication interface 132 is provided at the control unit 120 tohandle input and output functions and to facilitate communication withthe user node 190. For example, the communication interface 132 may be aWeb or Internet Protocol (IP) interface and the user node 190 mayinclude a Web browser for accessing and communicating with thecommunication interface 132. Communications over the network 180 can beimplemented using simple network management protocol (SNMP) or otheruseful protocols that facilitate management applications (such as thosethat would be operating on node 190) to query or command managementagents on the control unit 120 (such as those embodied in the remotemonitoring unit 128 and/or the remote management unit 130).

The remote monitoring unit 128 is provided to monitor a number ofparameters during the operating of the control unit 120. For example,the remote monitoring unit 128 may include measurement sensors for senseline voltages at outlets or in lines 152, 156, 162, 172 to extensionbars 150, 154, 160, 170 and in response, to communicate or transmit asignal(s) to the remote monitoring and management node 190 viacommunication interface 132. Sensors may also be provided to measureline status or on/off status of the lines 152, 156, 162, 172 and powerconsumption on these lines 152, 156, 162, 172 to measure operations atthe extension bars 150, 154, 160, 170 and connected loads or rackequipment. Again, these operating measurements are communicated to thenode 190 via the communication interface 132.

The remote management unit 130 provides operating management functionsfor the control unit 120 including local (or automatic control) andremote control functions including distributing power in response tocommands from the node 190 (or at an interface on the unit 120 (notshown)). The automatic controls may include staggered startup of eachoutput or extension bar 150, 154, 160, 170. The remote managementfeatures may include intelligent segment control such as remotelyproviding or terminating power to one or more of the extension bars 150,154, 160, 170. More specifically, the remote management commands for theoutlets may include configuration of each of the outlets of the controlunit 120 (such as via SNMP and interface 132), immediate on, sequencedon, delayed on, immediate off, and reboot (e.g., turning an outlet offand then back on immediately or with delays). Shutdown commands may alsobe issued to the control unit 120 to turn off all outlets. Other usefulmanagement commands may be issued by the node 190 and processed by theremote management unit 130, such as a cancel command to stop action onthe most recent command and an override command to cancel a previouscommand and replace it with a new command.

FIG. 2 illustrates one physical implementation and mounting arrangementfor a modular power distribution system in a rack. As shown, a modularpower distribution system 200 is installed in a rack 210 in the verticalor 0U-mounting arrangement to limit the amount of rack U-space beingused by the system 200 (e.g., to consume no or very little rackU-space). The rack 210 is a standard equipment rack with side wallshaving a row or strip 216 of mounting slots 216 and with corner supports214 also including mounting holes or slots. As shown, the control unit220 has its substantially planar housing 221 arranged vertically (i.e.,with a plane passing through the housing being substantially parallel tothe side walls of the rack 210). Mounting brackets or clips 226, 228 areprovided on the ends of the housing 221 of the control unit 220 forrigidly clipping to or mating with the holes or slots in the cornersupports 214. While shown in a generally upper position within the rackor cabinet 210, the control unit housing 221 can be mounted at anyuseful position or height within the rack 210. Outlet on/off switches222 are provided on the housing 221 and a control unit on/off switch 224is also included to allow local, manual control of the powerdistribution to the outlets of the housing 221 to which the power supplycords 252, 256, 262, and 272 are connected at housing 221. Power issupplied to the control unit 220 via inlet power cord 244 which isconnected to a power source or supply (not shown) external to the rack210.

The illustrated system 200 fans out power distribution within the rack210 by including four power extension bars 250, 254, 260, 270 that areconnected to control unit 220 with power supply cords 252, 256, 262,272. The power extension bars 250, 254, 260, 270 may be configuredsimilarly to the bars 150, 154, 160, 160 with similar maximum currents,with outlets or receptacles (such as with 8 outlets or receptacles asshown) or cord segments, and other described features. The bars 250,254, 260, 270 can be mounted at any position or height within the rack210 (typically, adjacent planned loads or equipment positions on theshelves). The configuration of the bars 250, 254, 260, 270 allowsmounting within the rack 210 without consuming rack U-space as the bars250, 254, 260, 270 have generally square or rectangular cross sectionsthat are similar in size to the corner supports 214, such that the bars250, 254, 260, 270 either extend only slightly beyond the cornersupports 214, are coplanar, or are actually recessed from the surfacesof the corner supports 214. As shown for bar 270, mounting clips orbrackets 274, 276 are provided on the ends of the bar 270 for rigidlymounting the bar 270 to the row 216 of mounting holes or slots on theside wall of the rack 210, which provides flexibility in the positioningof the bar 270 at nearly any position within the rack 210. As shown,cable management is significantly improved with only four short supplycables 252, 256, 262, 272 being used to supply 32 outlets (at least inthis embodiment) from which 32 loads can be supplied with relativelyshort jumpers.

FIG. 3 illustrates some of the mounting and configuration flexibilityprovided by the modular power distribution systems of the invention. Apower distribution system 300, with several similar components, is showninstalled in the rack 210. As shown, the housing 221 of the control unit220 is mounted horizontally in the rack 210 with mounting clips 226, 228being used to mount the housing 221 to corner supports 214. The housing221 is relatively thin so as to take up as little rack U-space aspossible while still providing desired functions (such as 1U, 0.5U, orless thickness). In one embodiment, the housing 221 is about 17.5 inchesby about 1.62 inches by about 13 inches (width by height or thickness bydepth). The depth may be maintained at less than half the depth of therack 210 to allow two control units 220 to be mounted back to back,horizontally, which is useful in modular power distribution systems thatutilize two control units 220 to distribute power in a rack 210.Alternatively, when two units 220 are installed in a single rack 210,the units 220 may be mounted adjacent to each other but top to bottom orbe mounted in a spaced apart fashion at two differing locations withinthe rack 210. In the system 300, only two extension bars 260, 270 areprovided and are attached to the control unit 220 by cords 262, 272,respectively. Of course, more or fewer extension bars may be utilized inthe system 300 (or in system 200).

FIGS. 4 and 5 illustrate one embodiment for a control or core unit 420(such as would be used in systems 100, 200, and 300). As shown, thecontrol unit 420 includes a housing 421 that is rectangular in shape andhas a thickness or height, H that is selected to allow the control unit420 to be mounted either in a vertical or horizontal mounting (asdescribed in FIGS. 2 and 3) without requiring much if any rack U-space.In most embodiments, the thickness or height, H, is less than or equalto about 1U and in some embodiments is less than about 0.5U to allowstacking of 2 control units on a single shelf. The thinness of thehousing 421 enables 1U or less horizontal mounting, which leavesdesirable rack U-space for other equipment in a rack.

As shown, a main ON/OFF switch 424 is provided for shutting down thecontrol unit 420 along with a main indicator light 430 for indicatingwhen power is provided to the unit 420 and when the switch 424 is placedin the ON position. An outlet switch or circuit breaker (such as a 15amp circuit breaker) 422 is provided for each power outlet of the unit420 (in this case 4 outlet switches 422 are provided to control, and inthe case of circuit breakers to overcurrent and surge protect, outlets450). Although not shown, indicator lights may be provided for each ofthe outlet switches 422. Power is supplied to the control unit 420 by anattached input power cord (which may, in some embodiments, be replacedby hard wiring directly to a facility input) 444 which is connected tothe housing 421, such as by a protective earth bonding screw 445. Thepower cord 444 is also attached to a power source or supply (such as afacility AC power source). Power outlets 450 are provided to allowconnection with standard power cords to extension strips or bars, andthe number and type of outlets 450 may be varied to practice theinvention. As shown, four outlets 450 (such as 4 IEC C19 outlets) areprovided to support power distribution to up to four extension bars. Inremote monitoring and/or management embodiments (such as that shown inFIG. 1), a plug-in for an interface connection is provided for acommunication signal cable to a network and/or remote monitoring andcontrol node, e.g., a SNMP or other connection.

FIGS. 6 and 7 illustrate two power distribution systems 600 and 700 thatillustrate the flexibility of the invention in allowing a user toconfigure power distribution in differing, modular ways to meet theirrack power needs. In a rack in the data storage and other industries, atypical power system block diagram may call for a primary and a backupAC input to three, four, or more high current loads.

In FIG. 6, two control units 620 and 630 without extension bars are usedto provide the AC transfer switch function or power distribution (fromprimary and backup power sources not shown) to the loads. As shown, amodular power distribution system 600 includes a rack 610 in which aprimary control unit 620 and a backup control unit 630 are mounted(either vertically or horizontally at a desired height in the rack 610).Four enclosures (such as servers or other computing or data storagedevice) 640, 650, 660, 670 are also mounted in the rack 610 and areconfigured for redundant power supplies with primary and backup inlets642, 644, 652, 654, 662, 664, 672, 674, respectively. During normaloperations, the primary control unit 620 distributes power to theenclosures 640, 650, 660, 670 via power supply cords 624 that areconnected individually to the power outlets 622 of the primary controlunit 620 and to the primary inlets 642, 652, 662, 672. The backupcontrol unit 630 supplies backup power via power supply cords 634 thatare connected individually to the outlets 632 and the backup inlets 644,654, 664, 674 on the enclosures 640, 650, 660, 670.

An alternate modular power distribution system 700 is shown in FIG. 7that demonstrates how the combined use of control units with extensionbars is useful for fanning out pluggable or other power supplies withina rack without cable confusion or loss of rack U-space. As shown, thesystem 700 includes a rack 710 in which three enclosures, such as highcurrent loads including servers and the like, 740, 750, 760 are mountedalong with a number of other rack devices 770. The high current loads740, 750, 760 are provided redundant power directly from a primarycontrol unit 720 and a backup control unit 730. This is achieved byconnecting primary inlets 742, 752, 762 via cables 726 to outlets 724 onthe primary control unit 720 and by connecting backup inlets 744, 754,764 via cables 736 to outlets 734 on the backup control unit 730.

Significantly, the other rack devices 770 are also provided redundantpower via extension strips 780 and 790 that are connected via cables726, 736 to outlets 724, 734 on primary and backup control units 720,730. The extension strips 780 and 790 have outlets 784, 794 (such as 8outlets or receptacles) that are then connected by jumpers or hardwiring to the other rack devices 770. Through the use of extensionstrips 780, 790, a number of enclosures 740, 750, 760 and other rackdevices 770 can be powered from one or two control units 720, 730 withminimal cables, with reduced cable run lengths, and with increasedavailable rack U-space (as the control units 720, 730 can be verticallymounted in a 0U mounting or horizontally mounted in a 1U or lessmounting and as the extension strips 780, 790 are corner mounted so asto not use an rack U-space).

As can be appreciated, the modular characteristics of the combined useof a core control unit with one or more sticks or strips significantlyenhances flexibility in growth (e.g., larger capacity and/or morefeatures) and provides simplified maintainability. Regardingflexibility, once a power distribution system is installed a user isable to upgrade the features and/or capacity in the control unit bysimply replacing the unit without modifying or replacing other portionsof the system, such as the extension strips which can remain in placeconnected to their loads. The extension strips or sticks can beunplugged from the core or control unit and the control unit can bereplaced with a control unit of greater capacity (e.g., a 16 amp unitcan be upgraded or changed to a 24, 32, or 40 amp core or vice versa) ora control unit with more or different control or power distributionfeatures or functionality, such as one with remote monitoring andmanagement features. In contrast, existing power distribution systemstypically require replacement of the entire power distribution systemand wiring the new system. Maintainability is improved because adefective part can simply be replaced without disturbing othercomponents of the power distribution systems of the present invention.For example, if an extension stick becomes defective, only thatextension stick needs to be replaced or repaired and if a coremalfunctions, the core can be readily replaced without the need forrewiring power distribution to loads or to the sticks.

Although the invention has been described and illustrated with a certaindegree of particularity, the present disclosure has been made only byway of example and that numerous changes in the combination andarrangement of parts can be resorted to by those skilled in the artwithout departing from the spirit and scope of the invention. A systemaccording the invention, such as system 100 of FIG. 1, may include 2 ormore control units within a single rack 110 each connected to extensionbars to quickly increase the number of power outlets within a rack, toincrease the modularity of power distribution control and distribution,and to allow differing loads to be powered within a single rack (i.e.,through the use of 2 different control units with different outputcharacteristics). In some embodiments of the invention, a single type ofextension bar is utilized while in some arrangements it is useful toprovide 2 or more differing extension bars, such as extension bars withdifferent numbers and/or types of outlets or including cord segments forsupplying power to various loads in a rack. While specific voltagesand/or currents have been described, the modular power distributionsystems are by nature voltage independent and worldwide compatible. Thepower distribution system typically conforms with power distributionindustry standards, e.g., conform to standards such as the NationalElectrical Code (e.g., NFPA 70) and the Standard for Safety ofInformation Technology (e.g., UL 1950, Standard for Safety ofInformation Technology Equipment, and/or IEC950).

I claim:
 1. A power distribution system for distributing power toelectrical or computer equipment mounted within an equipment rack oncorner supports, comprising: a control unit mounted within the rackincluding a power input for receiving power from a power source locatedoutside the rack, a power converter for converting the received power toan output electrical power, and a plurality of power outlets forproviding an electrical connection to the control unit and outputtingthe output electrical power; an extension bar mounted within the rackadjacent one of the corner supports and having an electrical power inputfor input of electrical power to the extension bar and a plurality ofpower outlets adapted to couple with and distribute electrical power toconducting elements that electrically connect the extension bar to themounted equipment; and an electrical power cable connected to one of thepower outlets in the control unit and to the electrical power input ofthe extension bar.
 2. The system of claim 1, wherein the control unitincludes a housing to which the control unit power outlets are mountedand brackets connected to ends of the housing configured for supportingthe housing at a selectable height within the cabinet on two adjacentones of the corner supports, whereby 0U of rack U-spacing in theequipment rack is utilized by the housing.
 3. The system of claim 1,wherein the control unit includes a housing to which the control unitpower outlets are mounted and brackets connected to the housingconfigured for supporting the housing in a horizontal position betweenthe corner supports and wherein the housing has a thickness of less thanabout 1U.
 4. The system of claim 1, further including a second extensionbar within the rack adjacent one of the corner supports and having anelectrical power input for input of electrical power to the secondextension bar and a plurality of power outlets adapted to couple withand distribute electrical power to conduction elements that electricallyconnect the second extension bar to the mounted equipment.
 5. The systemof claim 4, wherein the power outlets of the second extension bar differfrom the power outlets of the extension bar.
 6. The system of claim 1,wherein the control unit includes overload protection and an outputcircuit breaker for each of the power outlets in the control unit. 7.The system of claim 1, wherein the control unit includes a networkcommunication interface and is communicatively linked to a remotemonitoring and management node via a communication network and thecommunication interface.
 8. The system of claim 7, wherein the controlunit includes a monitoring system for sensing operating parameters forthe control unit and in response, transmitting monitoring signals to theremote monitoring and management node.
 9. The system of claim 8, whereinthe operating parameters are selected from the group consisting ofoutput line status, power consumption at the power outlets, and outputline voltage.
 10. The system of claim 7, wherein the control unitincludes a management system responsive to command signals from theremote monitoring and management node to operate the control unitincluding selective power distribution to the power outlets.
 11. A powerdistribution system for mounting within an equipment rack to distributeelectrical power to devices mounted within the equipment rack from anelectrical power source external to the equipment rack, comprising: anelongate first extension bar having a power inlet and a plurality ofpower output connectors adapted to couple with electrical conductorelements that electrically connect each of the power output connectorswith one of the mounted devices and further including means for mountingthe first extension bar in a first position adjacent to andsubstantially parallel to a corner support of the rack; an elongatesecond extension bar having a power inlet and a plurality of poweroutput connectors adapted to couple with additional ones of theelectrical conductor elements that electrically connect each of thepower output connectors with one of the mounted devices and furtherincluding means for mounting the second extension bar in a secondposition adjacent to and substantially parallel to the corner support ofthe rack; a control unit mounted within the rack including a power inputfor receiving power from the external power source and a plurality ofpower output connectors to output the received power and to couple withelectrical conductor elements that electrically connect a first one ofthe power output connectors with the power inlet of the first extensionbar and a second one of the power output connectors with the power inletof the second extension bar.
 12. The system of claim 11, wherein thecontrol unit includes a housing with means for rigidly mounting thehousing to two adjacent ones of the corner supports of the rack andwherein the housing has a thickness less than about a thickness of thecorner supports, whereby 0U of rack U-spacing in the equipment rack isutilized by the housing.
 13. The system of claim 11, wherein the controlunit has a current rating selected from the range of about 16 amps toabout 40 amps.
 14. The system of claim 11, wherein first and secondextension bars include at least six of the power output connectors. 15.The system of claim 11, further including a third and a fourth extensionbar each having a power inlet and a plurality of power output connectorsadapted to couple with additional ones of the electrical conductorelements that electrically connect each of the power output connectorswith one of the mounted devices and further including means for mountingthe second extension bar in a second position adjacent to andsubstantially parallel to the corner support of the rack and each havingtheir power inlets connected via an electrical conductor element to oneof the power output connectors of the control unit.
 16. The system ofclaim 11, wherein the control unit includes a network communicationinterface and is communicatively linked to a remote monitoring andmanagement node via a communication network and the communicationinterface.
 17. The system of claim 16, wherein the control unit includesa monitoring system for sensing operating parameters for the controlunit and in response, transmitting monitoring signals to the remotemonitoring and management node.
 18. The system of claim 17, wherein theoperating parameters are selected from the group consisting of outputline status, power consumption at the power outlets, and output linevoltage.
 19. The system of claim 16, wherein the control unit includes amanagement system responsive to command signals from the remotemonitoring and management node to operate the control unit includingselective power distribution to the power outlets.